Slope quality control for elevated slab ACI 117 4.8.2

[PrimeCivil]

I'm trying to interpret ACI 117 4.8.2. If anyone has experience I would love to compare how you typically verify the slope on an elevated slab roof using a level and tape.

I'm getting hung up on the line, "Interpolation or extrapolation of tolerances for dimensions greater than or less than 3m are not permitted."

What if your slope is less than 3m in length?

Also, the slope is unlikely to be a multiple of 3m.

We verified the slope over the length less than 3m, which to me is in violation of the "no interpolating" rules, but I couldn't think of a better way to get it done. For the sections over 3m, we overlapped the last two 3m sections.

 

[HTURKAK]

I copied and pasted the commentary relevant clause ;

A departure of 0.3% is approximately 3/8 in. over a distance of 10 ft. Tolerances are based on a 10 ft measured length. Interpolation or extrapolation of
tolerances for dimensions greater than or less than 10 ft are not permitted.


My interpretation is , the flatness of formed surfaces should be measured with by placing a 10 ft long straightedge on the surface with different orientation and measure the max. gap that occurs btw. straightedge and the surface..

 

[PrimeCivil]

Yeah, that's what I typically do for an interior floor for flatness.

So for a sloped surface it is acceptable to verify the overall slope then check flatness?